Its a term derived from the Hoxhaist perspective during the cold war ie that the soviet union is doing "socialist" imperialism and that they must be reprimanded and fought against. There were many US organizations that even took the next logical extension of the position that the soviet union os a greater imperialist threat than the US and NATO and therefore nato must be supported at all costs to fend off soviet union imperialism.

Obviously a bad take, but it rests in a weak understanding of dialectics first and imperialism second. Ultimately the issue is that in the age of imperialism, where tje primary contradiction is imperialism, the contradiction between capitalisms need to expand and export and the self determination of oppressed countries is directly at odds w each other. The correct resolution here is that self determination means and must mean whatever strikes the largest blow against imperialism first and foremost as imperialism is the most direct and all encompassing threat to self determination.

This is why stalin supported the struggle of the emir of Afghanistan even if it was a monarchist one as the enemy was imperialism, and any blow that weakens imperialism will in any case aid the self determination of the oppressed nations.

The other contradiction here is within revolutionary nationalism, as all nationalist struggles are a unity of classes of an oppressed nation. This means that there is a highly contradictory character of these revolutionary movements and for instance a possible melding of anti communist and anti imperialist ideologies. The reason we as communists support the struggle of oppressed nations is because we do not believe in nations, and thus understand that the only way the contradiction of nations can be resolved is in a geoolitical climate where there are no oppressor and oppressed nations, and we can move to the next stage of struggle